As Operative Hysteroscopy has gained popularity as a method to treat problems which formerly would have required open abdominal surgery, a number of complications of water and electrolyte imbalance secondary to the absorption of the irrigation fluid used during the procedure have become recognized..sup.1-5.
In open abdominal surgery, when irrigation fluids are instilled onto the surgical site, they are typically recovered using a suction apparatus in conjunction with a graduated collection bottle so that the surgeon has a reasonable estimate of the amount of fluid instilled, the amount recovered by suction, and, therefore, the amount of irrigation fluid available for systemic absorption.
In contrast, however, operative hysteroscopy generally requires injection of irrigation fluids under pressure to distend the uterus and because a relatively small opening is utilized during the surgery, the irrigation fluid is recovered as outflow. Because of the necessity of using this method of recovery, the collection and measurement of irritation fluids so injected is inaccurate with some irrigation fluid frequently being lost by absorption into the various drapes and bed linens as well as through spillage. In addition, the instilled irrigation fluid may be admixed with body fluids thereby adding to the apparent volume of outflow fluid. Thus the surgeon frequently has to guess whether or not, and if so, how much fluid is available for systemic absorption by the patient.
Irrigation fluids typically employed in operative hysteroscopy include, by example and not by way of limitation, 3% Sorbitol, Hyscon (comprising 32% Dextran 70 in water) and Saline.
Irrigation fluids are typically refrigerated and administered cold in an attempt to control bleeding.
Apparatus for sampling expired air are well known. Examples of such apparatus are shown in U.S. Pat. No. 2,795,223 to Stampe, U.S. Pat. No. 3,661,528 to Falk, and U.S. Pat. No. 4,297,871 to Wright, et al. Similarly, devices for measuring the alcohol content in exhaled breath, such as that shown in U.S. Pat. No. 4,736,619 to Legrand are also well known.
Similarly, the measurement of tidal alcohol in patients undergoing Transurethral Prostatectomy (TURP) to avoid many of the same complications as has been recognized in Hysteroscopy patients has also been documented..sup.6-13 Where tidal alcohol has been used as a measurement or indicator of the absorption of irrigation fluid, from 1% to 2% Ethanol by volume is added to the irrigation fluid before it is instilled in the patient.
However, Operative Hysteroscopy is fundamentally different from TURP in that higher injection pressures, on the order of 60-80 mm. Hg are used, and, unlike the TURP patient, if the Hysteroscopy patient has patent fallopian tubes, there is a direct pathway into the peritoneal cavity. In addition, whereas TURP is frequently performed using local anesthesia, such as epidural or spinal anesthesia, Hysteroscopy is frequently performed with the patient "asleep" under general anesthesia.
Accordingly there is need for a means for the detection and measurement of end tidal alcohol in patients who are under general anesthesia to determine the occurrence of the absorption of irrigation fluids.